Check engine light on, please help!

[element1290]

My check engine light came on shortly after installing my AEM CAI and I ran up to autozone and got my ecu scanned. The codes ran told me that the engine is running too lean at idle, can anyone explain to me what this may mean and what can be done to fix this issue. I have done some research but I have come up with nothing so i turn to you guys hoping for some help, thanks in advance.

 

[Blendercloud]

The first thing off the top of my head would be to ask you if you reset the battery after you did the install. If you did not, your fuel trims are probably way off.

 

[DetroitMS6]

Did you install the air straightener? AEMs are suppose to have an air straightener to help with fuel trims.

 

[bova80]

aem cai = mazdaspeed cai and there are tons of mazdaspeed cai with this problem.

 

[Raynman]

Quote the almighty crossbow from Mazda6tech:

What Does the Short and Long Fuel Trim have to Do With a P0171 Code?

A P0171 code (Check Engine Light) is thrown when the engine compares the Short Fuel Trim to the Long Fuel Trim and finds greater then a 9% difference. The Short Fuel Trim is basically a real time collaboration of data, which is a reflection of the current air/fuel ratio of the mazda6. The Long Fuel Trim is based on a default map (which is reset anytime you pull the negative battery cable, or reset your cel's with a scanner) and changes after each drive cycle by taking the SFT's data into itself.

Thus the computer has the capability to adapt its settings over time to a variety of conditions. If a change is introduced (more air from a CAI for example), and the SFT changes by a significant amount, the PCM marks a possible problem as a pending code. In the 4 cylinder this is a P0171 code, in the 6 cylinder this is a P0171 or P0174 code. If two concurrent drive cycles occur the PCM throws a check engine light, to let you know a difference is occuring.

This Cel does not necessarily mean that damage occurring...only that a difference has been noted. Based on UOA's (used oil analysis's) this difference is not changing or effecting engine wear in any way, shape, or form. Even with the additional air, at no point does the A/F ratio reach a dangerous "lean" condition.

Here are some A/F readings from the original injen intake. 14.7:1 is optimal fuel efficiency. 13:1 is optimal power delivery. Anything below 13 is rich.

@ 2500 rpm: 14.8
@ 3000 rpm: 12.8
@ 3500 rpm: 12.5
@ 4000 rpm: 11.9
@ 4500 rpm: 11.5
@ 5000 rpm: 11.0
@ 5500 rpm: 10.6
@ 6000 rpm: 10.2
@ 6200 rpm: 10.2

In quick conclusion...if you put on an aftermarket intake, there is a CHANCE that you may get a check engine light. Its not harmful to the car, but be forewarned.

 

[element1290]

The first thing off the top of my head would be to ask you if you reset the battery after you did the install. If you did not, your fuel trims are probably way off.

When it was installed the battery was off the entire time, it odd bc the light will come on and off as it pleases so it may be that?

 

[Blendercloud]

There was another post just recently that brought up the problems people have had with the AEM CAI continuously setting off the engine light. There was also talk about problems with the air straightener. The person said the light was nothing to really worry about, just an annoyance.